you can compress your image files to be sent via mig using your n91 mobile phone itself. no additional aplications or softwares required. use your multi media messaging option for this purpose. you will not be charged for your multi media messaging cuz you are not messaging anything. we just use the first steps of sending multimedia message from your cell til the image is compressed into a smaller size. follow these steps:
1.open your pic in ur phone gallery
2.press options
3.select send
4.select via multimedia
5.press options
6.select objects
7.press options
8.select open
9.press options
10.select set as wallpaper
now you will be asked to save the picture before sending. select 'yes'. now the picture you just saved will be of very smaller size.